FWIW, I had an HPtuners program on my laptop and spend many many hours logging and tuning my 02 Trans Am. (about 150 tunes all together).

When you reset the ECU, your fuel trims (LTFT and STFTs) are reset and have to learn. Same with your idle trims. While it's learning, the car may run slightly more rich or slightly more lean as it figures out the fuel trims.

But, it doesn't take long for your computer to learn the fuel trims. And any changes in performance would only be temporary.

Maybe that's how the aftermarket parts people are claiming huge dyno results. They add a part and reset the ECU and gain HP that way. I don't know.

 

I agree as well about the ECU; wasn't the one who originally made that recommendation. As far as the bracket being tight, not really. Rationale - Double check the other threads in here regarding track times for our cars. This was more or less an average of the low and high. Either way!

 

You are correct sir! The service manual calls it open loop

 

Yep. and when running off of o2 feedback..... closed loop. (they aren't very creative with the names.)

 

YEP thats when the sensors are warmed up and not in the warmup cycle.

 

^ Uh, no. You can run in closed loop the second the car is started if you go WOT.

 

when i was doing emission testing...we had to run the vehicle till its done warming up. at idle it would be in the warm up cycle until the vehicle reaches operating temperature, the ecu usually provides a richer mixture when the vehicle is cold. once warmed up the 02 sensors do their jobs. thats when we were supposed to run the emissions test. it has been a few years since i gotten out of the smog stuff but i do not recall anything about WOT the vehicle will go into closed loop even if its a cold start. i would think it would rather be in open loop at WOT to add more fuel to compensate the extra air coming through and to prevent a lean mixture.

please educate on me maybe im wrong but thats what i learn from my years in emission system and diagnostics.

 

soooo...... what happened?

 

The reason you want a car warm for emission testing is so the catalytic converter is at operating temperature.

If you go wide open throttle (WOT) the car is in closed loop operation i.e. it looks at various values from sensors and adjust fuel/timing from set maps.

 

yeah...where are the slips at?

 

Sorry for the lame question, but can anyone tell me how to launch using AT?

 

thats true but also to get the vehicle into normal operating temperatures. Have you ever heard of cold start or how it works? when the ecu increases the injector pulse width?
yea like i said earlier...when the o2 sensor is warmed up the vehicle is in closed loop.

from what i remember i thought the vehicle has to be in normal operating temps to be in closed loop but when cold and in WOT its in open loop;

where did you learn it was in closed loop in WOT?

back ontopic...i wonder what he ran

 

From: http://www.thirdgen.org/open-loop-closed-loop

Q: What is the difference between 'Open Loop' and 'Closed Loop'?

A: When the engine is first started, and rpm is above 400 rpm, the system goes into 'Open Loop' operation. In 'Open Loop', the ECM will ignore the signal from the Oxygen (O2) sensor and calculate the air/fuel ratio based on inputs from the coolant and MAF sensors, but mostly from a pre-programmed table in the memcal.

The system will stay in 'Open Loop' until the following conditions are met:

1. The O2 sensor has varying voltage output, showing that it is hot enough to operate properly. (This depends on temperature)
2. The coolant sensor is above a specified temperature about 40oC/104oF.
3. A specific amount of time has elapsed after starting the engine.

The specific values for the above conditions vary with different engines and are stored in the mem-cal. When these conditions are met, the system goes into 'Closed Loop' operation. In 'Closed Loop', the ECM will calculate the air/fuel ratio (injector on-time) based on the various sensors but mainly the O2 sensor. This allows the air/fuel ratio to stay very close to 14.7:1.

 

During WOT and Power Enrichment mode (depends on throttle position and RPM, you go from stoich 14.7:1 A/F to about 12.5:1) it is in Open loop. The car ignores o2 feedback and calculates a/f ratio based on tables.

stock o2 sensors aren't accurate when cold or during WOT. You can buy wideband o2 sensors that'll give accurate readings during WOT and use them for tuning. But, the car will still be in open loop.

 

When it comes to open vs. closed loop, o2 sensors aren't accurate while cold. They actually have heaters built into them to warm them up to be accurate sooner (to get into closed loop).

Like I said before, at WOT, the car ignores the o2 sensor feeback because the sensors aren't accurate anymore. It does still use MAF readings but ignores fuel trims completely (which is why it's called open loop).


If you log a car during PE mode and WOT, the fuel trims all go to zero.